1. Field of the Invention
The present invention relates to a die for forming a honeycomb structure and a manufacturing method of a die for forming a honeycomb structure.
2. Description of the Related Art
As a manufacturing method of a ceramic honeycomb structure, heretofore a method has been broadly performed in which the honeycomb structure is formed by extrusion using a die for forming the honeycomb structure, including a die base member provided with back pores for introducing a forming material (clay) and lattice-like slits connected to the back pores. In this die, one surface of the die base member is usually provided with the slits each having a width corresponding to the thickness of each partition wall of the honeycomb structure and arranged in a lattice-like form or the like, and the opposite surface (the other surface) thereof is provided with the back pores connected to the slits and having large open areas. Moreover, the back pores are provided at such positions where the lattice-like slits or the like intersect with one another, and the back pores and the slits communicate with each other in the die base member. Therefore, a forming material such as a ceramic material introduced through the back pores move from the back pores having comparatively large inner diameters to the slits having small widths, and is extruded through the slits to obtain a formed honeycomb structure article.
As such a die base member of the die for forming the honeycomb structure, for example, a plate-like member (a die precursor) made of one type of alloy such as a stainless steel alloy or a super hard alloy, or a plate-like member (a die precursor) obtained by bonding two different types of plate-like members is used (e.g., JP-A-2000-326318, JP-A-2003-285308 and JP-A-2006-51682).
However, the forming material such as the clay or the like has a high hardness and easily causes wear, so that in the die for forming the honeycomb structure, the inner walls of the back pores or the slits need to be strong against the wear. It is considered that in the die for forming the honeycomb structure, one plate-like member made of the super hard alloy having the high hardness is cut to form the back pores and the slits therein, but it is technically difficult to bore the plurality of back pores and slits in the super hard alloy having the hardness, and there is also fear that the walls of the slits might break down owing to the hardness of the super hard alloy.
On the other hand, in the heretofore broadly used die for forming the honeycomb structure, constituted of the plate-like members made of different materials of the stainless steel alloy and the super hard alloy, a defect that the die breaks down does not easily occur owing to the softness of the stainless steel. However, when the stainless steel having a hardness lower than that of the super hard alloy is used, the labor of a wear countermeasure such as the coating of the inner walls of the back pores or the like is required. Therefore, even the die for forming the honeycomb structure, constituted of the plate-like members made of the different materials of the stainless steel alloy and the super hard alloy, cannot fundamentally solve any problem.